Which drug may be used extralabel in some circumstances in a food-producing animal?

• A. Clenbuterol
• B. Phenylbutazone
• C. Vancomycin
• D. Nitrofurazone

Answer: (B)

Extralabel drug use in food-producing animals is only allowed under strict federal rules (AMDUCA) when there is no approved alternative for the condition in that species, and the use is guided by a veterinarian with careful record-keeping, proper withdrawal times, and adherence to safety safeguards. The drug can be used extralabel if it’s approved in some species or for humans, but not for the species in question, and only under the specific conditions laid out by law.

Phenylbutazone fits this scenario because, while it is not approved for use in food-producing animals, it may be used extralabel in certain circumstances under AMDUCA, with strict safeguards and withdrawal times. The other drugs listed have clearer prohibitions or are associated with safety or resistance concerns that preclude extralabel use in food-producing animals: clenbuterol is tightly restricted due to risk of human illness from meat; vancomycin and nitrofurazone have safety and resistance issues that prevent extralabel use in meat-producing species.